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kx250 lower shock bearing solutions

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my kx goes through lower shock bearings like crazy. its a bad design, i just cant keep grease in it. i have been trying to get a spherical plain bearing in there, but packaging issues make it difficult to seal. today i finally ordered one from ebay for $9 to attempt it; ill have to make an inner sleeve for it and figure out how to seal it with the stock sized seals. but i starting thinking about using a plain bushing instead. i have some "bearing brass" (forgot the alloy number) that i can throw on the lathe and make a bushing out of. my question is to how well this will hold up. i know it will work just fine, but for how long? and what would be the material of choice for the "inner race" with a brass bushing. or would a different material be better? steel on steel? delrin?tolerances? my goal is low maintenance, i have to replace this bearing about twice a year, my other bikes have the same or more milage on them with original bearings. i have materials and a lathe and mill. thoughts?

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Umm, I used the pivot works kit which is cheap garbage chinese crap, but it had a good sealing system and honestly, I never had that much of an issue. I packed it with waterproof grease and it seemed to hold up well.

That whole system wasn't very well thought out. I've worked on newer Kawi's and they seem to be better in that department. I think they just changed manufacturers.

I don't know how a home-made solution will be any better. But to put it in perspective, I was replacing those bearings every year.

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Umm, I used the pivot works kit which is cheap garbage chinese crap, but it had a good sealing system and honestly, I never had that much of an issue. I packed it with waterproof grease and it seemed to hold up well.

That whole system wasn't very well thought out. I've worked on newer Kawi's and they seem to be better in that department. I think they just changed manufacturers.

I don't know how a home-made solution will be any better. But to put it in perspective, I was replacing those bearings every year.

ive used pivot works, all balls, ive put my own kits together from a bearing shop, nothing lasts too long. i remade the inner race and some spacers for it last replacement to try and get a better seal with that stupid flanged 2 piece race. i was going to tear into it soon to see how it held up, but i know its due. i grease all my bearings at least twice a year, every other bearing on the bike still looks great every time i service them, i just clean em and regrease em, but that lower shock is always long gone.

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That's been my experience as well. In my opinion, Kawasaki's design just doesn't have enough surface area for the loads. The bearing needs to be wider.

Glad you picked that up, I didn't analyze it enough when I had my Kawi, but that makes sense.

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That's been my experience as well. In my opinion, Kawasaki's design just doesn't have enough surface area for the loads. The bearing needs to be wider.

that was my exact thought as well and the reason i havnt tried the spherical bearing yet. i had the idea a few years ago, but the only size made with the proper od has an even thinner race than the needle bearing, although all of its surface area is used instead of just the roller contact points. hence the brass bushing, much more surface area. another problem with the stock full compliment needle bearing is grease retention, full compliment needles dont have the reservoir room and tend to push out what little grease is there. that would be an issue with a bushing as well, but the beauty there is brass doesnt require mush lubrication, the question is if it will "egg" out quickly.

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I go through lower shock bearings like crazy on my Yamahas, too. It's not for lack of lubrication, they just get lots of abuse. I consider them a maintenance item so I just added three KYB bearings to my last suspension order. Much cheaper than the kits and I don't have all the spare uppers and seals.

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Sean I am using a bushing that has a teflon inner, not sure the brand but came in a lower shock bearing kit from RMMC (I can look if you want, still have the package in the shop) along with a bearing and you use the one you want so I tried the bushing and it has held up much better for me.

Ed

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Sean I am using a bushing that has a teflon inner, not sure the brand but came in a lower shock bearing kit from RMMC (I can look if you want, still have the package in the shop) along with a bearing and you use the one you want so I tried the bushing and it has held up much better for me.

Ed

i know some of the newer pivot works kit come with a teflon spherical bearing, but the kx kit isnt one of them from what their site said. maybe they have changed the kx kit to include it. but yea look for me if you would, thanks!

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It is a All Balls kit and it comes with the needle bearing and this bushing that is the same OD and ID as the bearing and you can use either. It is no a spherical bearing just a teflon lined bushing, the lining looks like the newest king pin bushings I was using at work.

Ed

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It is a All Balls kit and it comes with the needle bearing and this bushing that is the same OD and ID as the bearing and you can use either. It is no a spherical bearing just a teflon lined bushing, the lining looks like the newest king pin bushings I was using at work.

Ed

black teflon pan looking stuff? ptfe? i have some of those i could use sitting on a shelf somewhere. they press in and are only a mm or so thick, so i would make a bushing for it. ive milled out my rear brake lever pivot to accept one of those, as you know how quickly and severely those slot themselves out.

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No it is a bronze bushing with a yellow woven plastic (teflon I think) in the inside that is very thin. The last 5 years or so that I worked on the snow plows at work had new king pin bushings made the same way. It is holding up well.

Ed

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No it is a bronze bushing with a yellow woven plastic (teflon I think) in the inside that is very thin. The last 5 years or so that I worked on the snow plows at work had new king pin bushings made the same way. It is holding up well.

Ed

awesome, that gives me a good direction to go. thanks ed

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Sean -- I pulled the entire bearing out and put in a nylon bushing in its place. No grease, no lube, etc -- it lasted a long time. Cheap solution, easy to try. I found some nylon stock in lowes hardware section, my lower link was already wallowed out, drilled it out a little larger to fit the nylon, pressed in the nylon bushing, drilled it out to fit the shock bolt, trimmed the sides to the correct width - done. I think brass bushing would also work, but might not absorb the impact as well ?? Either way, its not that hard to try both.

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Sean -- I pulled the entire bearing out and put in a nylon bushing in its place. No grease, no lube, etc -- it lasted a long time. Cheap solution, easy to try. I found some nylon stock in lowes hardware section, my lower link was already wallowed out, drilled it out a little larger to fit the nylon, pressed in the nylon bushing, drilled it out to fit the shock bolt, trimmed the sides to the correct width - done. I think brass bushing would also work, but might not absorb the impact as well ?? Either way, its not that hard to try both.

i have a huge chunk of nylon and some delrin:ride:

i got the spherical in today, way to small race width for my linking.

IMAG0139.jpg

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Out of curiosity, does anyone know why they use needle bearings in the first place? Old 4-strokes all had swingarm bushings inplace of bearings, and they lasted alright.

Is it a matter of stiction? I'd think lighter, cheaper bushings would be beneficial if the only concern was service life. And in off-road trucks they use urethane bushings that hold up very well to truly awful abuse...

Just curious if anyone knows?

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Out of curiosity, does anyone know why they use needle bearings in the first place? Old 4-strokes all had swingarm bushings inplace of bearings, and they lasted alright.

Is it a matter of stiction? I'd think lighter, cheaper bushings would be beneficial if the only concern was service life. And in off-road trucks they use urethane bushings that hold up very well to truly awful abuse...

Just curious if anyone knows?

I have always wondered that myself. I have some extra urethane bushings I was thinking about using if I could turn them on the lathe to fit the kx. my 95 kx100 has a rubber bushing in the upper location, its original and still going strong.

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Out of curiosity, does anyone know why they use needle bearings in the first place? Old 4-strokes all had swingarm bushings inplace of bearings, and they lasted alright.

Is it a matter of stiction? I'd think lighter, cheaper bushings would be beneficial if the only concern was service life. And in off-road trucks they use urethane bushings that hold up very well to truly awful abuse...

Just curious if anyone knows?

GUESSING -- but -- in the competitive world of dirt bike magazine reviews and Pro MX, small little differences in feel can make a big difference in selling bikes. I am going to guess that some pro MX mechanic figured out the suspension might work 0.5% better with needle bearings instead of bushings. They dont care about maintenance and durability -- they are all about getting every possibly advantage. They get paid to disassemble and reassemble the bike every single week anyway, so a little more maintenance is not a big deal to them.

Just guessing.

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I know this is an old post, but I was just going over my linkage the other day and found everything looked great except the lower shock bearing.

It was bone dry and rusted, some of the needles had broken and the sleeve was trashed. This was surprising because it wasn't that old.

I've ordered a replacement kit, but i also found some bronze sleeve bearings that are the same size as the needle bearing and are inexpensive.

Any thoughts as to if that would be more durable than the needle bearings?

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